[email protected] wrote:What is the value of 10 - 8 + 6 - 4 + ... - (-20) ?
8
10
12
14
16
Look for a PATTERN.
Sum of the first
2 terms = 10 - 8 =
2.
Sum of the first
4 terms = (sum of the first 2 terms) + 6 - 4 =
4.
Sum of the first
6 terms = (sum of the first 4 terms) + 2 - 0 =
6.
Note the pattern exhibited by the values in red.
If n is EVEN, then the sum of the first n terms = n.
From 10 to -20 there are a total of 16 even integers.
The sum of the first 16 terms of the sequence = 16.
The correct answer is
E.
On the GMAT, a formula for the sequence would be given.
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